When silicate units are linked together,they form which type of structures?

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$: $H_2\underline{S}O_5 + H_2O \longrightarrow H_2SO_4 + H_2O_2$

Match the following:

List-$I$ (Compound)	List-$II$ (Silicate)
$A$. Zircon $(ZrSiO_4)$	$P$. Ring/Cyclic
$B$. Talc $(Mg_3(OH)_2(Si_2O_5)_2)$	$Q$. Ortho
$C$. Thortveitite $(Sc_2Si_2O_7)$	$R$. Pyro
$D$. Benitoite $(BaTiSi_3O_9)$	$S$. Sheet

Which of the following substances is used in smoke screens?

The correct statements with respect to halides of group $14$ elements are:
$I$. Both $CCl_4$ and $SiCl_4$ undergo hydrolysis
$II$. $GeX_4$ is more stable than $GeX_2$
$III$. $PbX_4$ is less stable than $PbX_2$
$IV$. Stability of dihalides decreases down the group.

Which of the following is a three dimensional silicate?